


Fanaticism

by NyxToNine



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Canon-Typical Violence, Emotional Manipulation, Emotional/Psychological Abuse, F/F
Language: English
Status: Completed
Published: 2020-12-13
Updated: 2020-12-13
Packaged: 2021-03-10 22:41:21
Rating: Mature
Warnings: Graphic Depictions Of Violence, Major Character Death
Chapters: 1
Words: 2,267
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28054803
Author URL: https://archiveofourown.org/users/NyxToNine/pseuds/NyxToNine
Summary: Byleth has given herself, mind, body, and soul, to Edelgard. There is no length to which she will not go, and no battle she will not fight.A more manipulative take on Edeleth, set during the defense of Garreg Mach.
Relationships: Edelgard von Hresvelg/My Unit | Byleth
Comments: 2
Kudos: 72





	Fanaticism

The Sword of the Creator ripped through the monk with a terrible ease, blood painting the blade and ground a dark sanguine. Byleth could feel the warm liquid dribble down her wrist, but was utterly indifferent to its presence. Her only goal right now was to defend Edelgard, the Black Eagle Strike Force, and the monastery, in that order. Her devotion to the Adrestian Emperor was absolute, and she had given herself entirely to the cause for which Edelgard fought. If the Church of Seiros was an enemy of the Empire, Byleth would cut them down without hesitation.

The Church had mounted an assault on the captured Garreg Mach Monastery, which the Black Eagle Strike Force had taken as a base of operations, and so the Ashen Demon was sent out to force them to retreat. She had been instructed by her emperor to cut around and eliminate the man leading the charge, Seteth, in order to break their morale. She would make no time for anything or anyone who would stand in the way of the objective she had been personally given by the Adrestian Emperor.

Byleth moved quickly and quietly, for although she took pleasure in gutting the emperor’s enemies, her mission prioritized speed over all else. The main forces of both sides were clashing in a relatively open space in front of the monastery steps, and Byleth was moving down a side path with denser foliage and fewer combatants. There would be no further interruptions.

Treading lightly, the green of Seteth’s hair slowly came into view, only for a recognizable voice to sound from nearby. “Professor!” Flayn exclaimed from just a few paces behind her, voice tinged with both confusion and betrayal.

In an instant the mercenary whipped around, Sword of the Creator unfurled, and lashed out with the unstoppable might of the Goddess Sothis. Flayn’s reaction speed was deceptively high, getting only a small gash in her forearm as she dodged away. Surprise colored her features, as if she didn’t expect to be attacked on a battlefield.

In truth, Byleth did feel an unpleasantness in turning her blade on a former student, she might even go so far as to describe it as painful. But these moments, the uncomfortable feelings of fighting people who she may have once have described as friends, were not important. All that she lived for was the in-between, the fleeting bits of time she got with her emperor. The look in Edelgard’s eyes when she did exactly as she was told, the praise she got after a particularly exemplary battle. The world seemed in higher definition then, a color and vibrancy that drained away otherwise. She would do anything for just a few more seconds of that precious time, including ending the lives of former students.

Flayn once more opened her mouth to say something, but the Sword of the Creator was already tearing through the air again, aiming to end the encounter in a single strike. Flayn jumped backwards, this time evading the teeth of the sword entirely, and fired back a powerful blast of white magic, force becoming her only hope of stopping her old teacher.

The magic connected with Byleth, who had made no attempt to avoid it, and though she felt the exhaustion and searing heat of offensive holy magic, she knew that she still had strength enough to fight Seteth after finishing Flayn. Pushing her muscles into action, Byleth flew forward with far more force than seemed possible for someone who had just been directly hit by such a powerful spell. Flayn hadn’t been expecting her attack to do so little, and while her reflexes were still quite fast, this time Byleth was quicker, stabbing her blade at the girl’s heart and running it through with the relic, splattering blood across the front of Byleth’s light armor. Slowly, she retracted the blade from the limp body of her former student and turned away from the gruesome scene to focus once more on her target.

From across the clearing, Seteth cried out, “Flayn!” His eyes were fixed on where she lay on the ground, though if there was any life left in her, she didn’t show it. His shock drew the attention of the Knights who were flanking him, though when their eyes fell on the girl’s lifeless body, it seemed to transfix them totally. Seteth, on the other hand, charged directly at her atop his wyvern, letting out a guttural scream as he took aim with his spear.

Byleth deflected the blow easily, but Seteth continued to swing with speed much greater than had been expected, and each time he came closer to skewering her as she had Flayn. The knights who had been accompanying Seteth had also gotten a hold of themselves, and although they moved much slower on foot than Seteth did on his wyvern, it was clear that Byleth would be overrun if she didn’t act soon. As Seteth swung his spear down at her shoulder, the Ashen Demon whipped the spiked tendril of the Sword of the Creator at Seteth, allowing him to dig into her left shoulder blade in exchange for taking a chunk out of his side. It was incredibly painful, but the pain dulled as she drilled a reminder into herself that she had been sent here to do only one thing, and there was no worse outcome than failure.

Seteth let out a gasp of pain when the blade connected, and in the brief moment that he flinched, Byleth was upon him once more, cutting through the armor he wore with the unparalleled might of a relic. Letting out a pained groan, Seteth fell from his wyvern into a heap on the ground, the beast taking flight away from the battlefield. The knights who had been coming to assist him seemed more hesitant, but they charged all the same, hoping to take down Byleth in her weakened state. Unfortunately for them, they lacked the experience or respect for the Sword of the Creator that Seteth had possessed, and Byleth tore through both of them before they could even get close enough to strike, the range of the weapon clearly being unexpected.

Finally catching her breath, Byleth could see other members of the Black Eagle Strike Force push through to the clearing, Ferdinand leading them on horseback. She attempted to walk over and inform him of her success, but after just one step forward she felt her legs give out, the world around going dark as she lost consciousness.

* * *

Byleth awoke to the gentle touch of healing magic, caressing where the spear had dug into her. It was pleasantly warm, soothing the pain that was much more pronounced now that she was outside the din of battle. Opening her eyes slowly, she could see the familiar green of Linhardt’s hair, and the dark bags that sat under his eyes. He was knelt beside the bed she lay in, pallid complexion lit by the sunlight streaming through the windows of the infirmary. He seemed to be kept awake only by the thrum of the magic that he was exhausting himself using. As she studied him, Linhardt took notice of her shift in breathing, and let out a loud yawn.

“Good morning, Professor. How are you feeling?” Linhardt asked, the tiredness in his voice even more evident than on his face.

The gears in Byleth’s head began to turn as she recalled all that had happened before she passed out. Realizing that she had never seen the end of the battle, there was only one question on her mind. “Did we stop the Church?”

“We did,” the healer answered simply. All at once, Byleth felt apprehension wash away, her inability to stay upright hadn’t cost them victory. Losing the monastery as a staging ground would have been bad, but disappointing Edelgard would have been even worse.

“Then I’m fine. I’m sure I’ll recover.”

Linhardt looked at her like he objected very strongly to that assessment, but after thinking it over, he simply stood and headed for the door. “By the way, Her Majesty wanted me to let her know when you woke up. I expect she’ll be in to visit at some point.” With that, he left the infirmary, shutting the door tightly behind him.

Byleth, for her part, felt every second drag on as she eagerly awaited the visit from the most important woman in the world. She had been injured much worse than she had meant to be, and while it did mean she would have to spend quite a bit of time in recovery, she knew that as long as she was willing to give life and limb to Edelgard, she would always be cared for in turn.

There was a clarity of purpose in Byleth’s life whenever she heard Edelgard speak, and her every touch was manna from heaven, an endless ocean of strength she could never drink deeply enough from. Byleth’s very existence was contingent on Edelgard, she would surely wither and die without her light to guide her.

Consumed in her thoughts, Byleth waited for the minutes to tick by before the infirmary door finally swung open to reveal Edelgard Von Hresvelg, the last Emperor of Adrestia, adorned in the regalia she always wore when not heading into battle. All at once, the beautiful platinum hair that had been fashioned into buns gleamed so much brighter than any material Byleth had ever seen. Her lilac eyes were impossible to match, a color all their own, and her dress was the inverse, carrying the red of a rose as if it were made of its petals. In short, Edelgard was a figure that seemed, as she stood before Byleth, absolutely divine.

“I’m glad to see you’re okay, Professor.” It was the same title everyone addressed her with, but the way Edelgard said it imbued with an enchanting quality, as if it was both a term of endearment and a show of respect. Just hearing it come from Edelgard’s lips made the cold of the world retreat, at least for a while, and the warmth of adherence took its place.

“I got rid of Seteth, like you asked.” For all the poetry in her heart, Byleth could only give a report of what had happened in her battle. There was no need to say more, their relationship perfectly understood by both parties.

“I see. I heard Flayn also fell in battle, and that you were responsible.”

Byleth’s voice caught. “That’s right.” She had been told to take out Seteth as quickly as possible, although no one had suspected that Flayn would also take to the field. At the time, she had seen Flayn only as an enemy combatant, and had dispatched of her as such. She hadn’t considered that perhaps Edelgard would not want her former classmates killed.

“Did you have a problem fighting her?” Edelgard asked. Relief washed over Byleth once more as she realized she made the right call by getting rid of the girl.

“Not at all,” the devotee answered sincerely. If Edelgard approved, she held no regrets.

“Good.” Edelgard smiled kindly, and the world felt so right. The pain of being torn into by a spear or the uncomfortable feeling she got when killing a student were meaningless in the face of such affection from her goddess. There was no higher purpose than this, and Byleth knew it for sure whenever she saw her emperor smile.

“But,” Edelgard added, “I must say that I am concerned about your injuries.” Although it was to be expected, Byleth hadn’t been looking forward to this. She had done worse in battle than she should have, and would be indisposed for longer than would otherwise be necessary, simply because she had been reckless.

Byleth averted her gaze, speaking softly in apologetic supplication. “I’m sorry, Your Majesty. I should have been more careful.”

“Look at me, Byleth.” She winced at the use of her name; Edelgard only used it when disciplining the mercenary. Nevertheless, Byleth made eye contact with Edelgard, and found that though her stern gaze was fearful in a way, it still carried with it the love that had earned Byleth’s undying allegiance. 

“I need you to take better care of yourself. This war isn’t over yet, and you can’t just throw yourself into every battle as though it was your last. I expect better from you in the future.” It was a short reprimand, but the sting of failure was painful. Despite that pain, however, these moments, too, were precious to Byleth. She understood that Edelgard only criticized because she cared, that pain was borne of inability, and the emperor was harsh only because she had to be. Edelgard would protect her even when she failed to care for herself, and Byleth’s greatest source of comfort came in knowing that she could relinquish herself to the only person who she knew would always be there for her, and in that powerlessness was the peace that she yearned for. All she ever needed to do was put her trust in the most trustworthy woman she had ever met.

“I’ll do better. I swear it.” Byleth meant it, she would do her best to adhere to the emperor’s wishes, even if it went against her instinct to not factor in her own well being.

“Good.” Edelgard smiled at the Ashen Demon once more, and in those enthralling lips, Byleth saw the only life she would ever need, serving eternally at the beck and call of Edelgard Von Hresvelg.

“I love you,” she whispered.

“Good.”

**Author's Note:**

> I like this pairing quite a bit, but I had the idea for this recently and decided to try my hand at writing it, despite how unsettling it is. While I still feel it could be a lot better, after talking with some friends I decided to post it anyway, if only to see what other people think of it. I greatly appreciate any and all feedback.


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